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The Article Details The Reasons For Declining A/C Efficiency With Age.     Al’s Plumbing, Heating & A/C in Plano, Texas provides maintenance & repairs for all brands of Central A/C, Gas & Electric Furnace, and Heat Pumps.    Additionally we sell and install new HVAC Systems from American Standard (same company as Trane), Ameristar (same company as American Standard) and Coleman HVAC (same company as York HVAC).

Al’s also provides full service plumbing maintenance, repairs and replacements for every plumbing component in your home.  Al’s sells and installs Rheem Professional Series gas & electric water heaters, and tankless water heaters.  Al’s is near your home in Plano, TX; Allen, TX; and Frisco, TX.  We service all homes in southern Collin and Denton Counties with no additional travel charge.

Call Al’s today to discuss any concerns or problems you have with your HVAC System or Plumbing.  We will arrange an appointment at your convenience and offer 24/7 Emergency Service.

 

Image Source: Dreamstime.com

Declining Central Air Conditioner Efficiency With Age

There are many opinions about declining air conditioner efficiency with age.   We found a 2018 Long-Term Scientific Study that details declining air conditioner efficiency with age — and by how much. 

The Research Study reported findings on declining efficiency of residential Central A/C and heat pumps over a period of 2–5 years.   The findings were based on 56 residential air conditioners and heat pump in Florida homes — with over 1,500 hours of A/C use per year. 

Click Below To Read The Research Report:

 Scientific Study Report On Declining Air Conditioner Efficiency With Age

Primary Causes Of Declining Air Conditioner Efficiency With Age:

Click Here To See A Diagram Of A Central Air Conditioner & Furnace: HVAC System With Attic Ductwork

  • First we will discuss the biggest reasons for declining air conditioner efficiency with age
  • At the end of this article we present our summary of the Research Study’s findings.  We provided a link for the full report. 

 

Leaking Ductwork — Decrease In Cooling Efficiency:  -10% to -25%.

Most homes lose 10-25% of the cooled / heated air through leaks in ductwork. *4

  • Typical ductwork in North American homes reduces the HVAC system’s efficiency an average of 43% . **  Poorly designed or installed ductwork  typically restricts air flow.  This causes the HVAC System to work harder and longer — which wears it out faster and increases cooling & heating bills.

** Source: https://www.nationalcomfortinstitute.com/pro/index.cfm?pid=1779

  • Older DFW homes’ metal  ductwork may not have been sealed when installed— or was sealed with duct tape.  Duct tape fails within days when subjected to the temperatures in DFW attics.
  • Workers in the attic can bump ductwork and break seals.
  • Over the years, ductwork seals often fail due to attic temperatures during DFW summers (up to 160 degrees).
  • It’s common for older DFW homes’ metal ductwork to leak air through gaps that weren’t sealed when the home was built.

Click Here To See A Large Gap Between The Ductwork And Ceiling: Gap Between Heat Vent & Ceiling

  • Flexible ductwork can become twisted, kinked, crushed, or torn.

Click Here To See Damaged (torn) Flexible Ductwork: Damaged (torn) Attic Ductwork

Click Here To See Crushed & Improperly Installed Flexible Ductwork:Crushed Flexible Ductwork

Mice sometimes chew holes in flexible ductwork.    Click Here To See Damaged Flexible Ductwork: Attic Ductwork With Holes

 

Copy The Link Below Into Your Browser For An Entire Article About Poorly Installed Flexible Ductwork: https://www.energyvanguard.com/blog/signs-of-a-bad-duct-installation

 

Dirty Furnace Filter — Decreased In Efficiency: Up to -15%.

dirty air filter on left. New air filter on right.

Image Source: Can Stock Photo

Shown: A very dirty furnace filter on left.  A new, clean filter on the right.

The United States Department Of Energy (DOE) States: “Replacing a dirty or clogged filter can lower your air conditioner’s energy use by up to 15%. **

** Source: https://www.energy.gov/energysaver/maintaining-your-air-conditioner

 

Dirty Indoor Cooling Coil (evaporator coil) — Decrease In Efficiency: Up to -19%.   

NOTE:  The indoor cooling-coil (evaporator coil) is inside the furnace or ductwork and can’t be seen without removing a panel.

The home’s indoor air passes through the indoor cooling-coil (evaporator coil) while the blower fan is running.    With the A/C on your home’s indoor air passes through the indoor cooling-coil to remove the heat and the humidity.  You must have a clean indoor cooling coil your air conditioner to perform at maximum efficiency.  If the coil is clogged the A/C to run longer & harder.

A clogged indoor cooling coil reduces the amount of air-flow through the coil.   One study says that if the indoor cooling coil is 1/3 clogged — it reduces A/C’s cooling ability by as much as -19%.  So, it’s fair to say 1/3 clogged indoor cooling coil increases cooling cost by +19%.  It also causes the HVAC system to run 19% longer and harder — and wear out at least 19% faster.  *5

The indoor cooling coil is wet when the A/C is running.   Because it’s wet dust can easily stick to the coil.

Dust & water create a perfect environment for mold growth.  When the indoor cooling (evaporator) coil is molded — when the furnace blower fan is running — it’s blowing mold-spores all over your home.  The photo we provided shows the dust clogging the indoor cooling coil to be black with mold.,

Click Below To See A Diagram Showing The Location Of The Indoor Cooling (evaporator) A/C Coil: 

Location Of Indoor Cooling (evaporator) Coil

Click Here To See A Clogged & Molded Indoor Cooling (evaporator) A/C Coil: 

Dirty & Molded Indoor Cooling (evaporator) Coil

Click Here To See A Frozen Indoor Cooling Coil: Frozen Indoor A/C Cooling Coil

Note: A Frozen Indoor Cooling Coil Is Due To:

  • 1. Not enough air flowing through it (typically because of a dirty air filter).
  • 2. Low refrigerant charge.

*5 Source: https://www.airah.org.au/Content_Files/TechnicalPublications/hvac-factsheet-cleaning-coils-09-13.pdf

 

Dirty Outdoor A/C Outside Unit (condenser) Coil —  Efficiency Decrease: Up to -30%. 

central air conditioner outside unit

Image Source: DreamsTime.com

The U.S. Dept. Of Energy (DOE) States:

“A dirty condenser coil can increase outdoor unit energy consumption by up to 30%.”  ***

Click Below To See Before & After Cleaning Photos Of An Extremely Dirty Outdoor A/C Unit Coil:

Before & After Cleaning Photos Of Clogged Outdoor A/C Unit Coil

*** Source: https://www.buildings.com/article-details/articleid/8282/title/clean-hvac-system-coils-save-energy

 

Dirty Furnace Blower-Fan Motor And/Or  Dirty Furnace Blower-Fan Wheel

Click Here To See A Very Dirty Furnace Blower Motor: Very Dirty Furnace Blower Motor

Click Here To See A Very Dirty Furnace Blower-Wheel:  Very Dirty Furnace Blower Wheel

Furnace filters don’t remove all the airborne dust flowing through them.   If filters were that efficient — they would restrict air-flow through the HVAC System.

Over time, even with the best furnace filter maintenance, dust will build up on the blower fan and the blower motor.  A dirty blower fan cannot move as much as as it’s designed to.   A dirty blower motor will overheat.  This will affect its performance and cause it to wear out faster.

air conditioner refrigerant and gauges

Shown: Air Conditioner Refrigerant-Tank & Installation Gauges

Image Source: Shutterstock

Low Refrigerant Level.  Efficiency Decrease: Up to 100%

To cool at maximum efficiency, an air conditioner (or heat pump) must be fully charged with refrigerant.  The lower the refrigerant level — the lower the cooling efficiency.  Low refrigerant causes the A/C to run longer & harder — reducing its lifespan and increasing cooling bills.   During peak summer heat, an A/C that’s low on refrigerant won’t be able to keep the house cool.

The refrigerant must stay at a specific charge / level.  If the refrigerant level drops, it reduces the air conditioner’s cooling  ability.  Refrigerant doesn’t get used up.  If refrigerant is low — it’s due to; a leak (most common), corrosion, or loose connections somewhere along the refrigerant line.

The report stated: “A system 20% low of refrigerant (in a 3-ton / 36,000 BTU system)  causes up to -24% decrease in cooling abilty at a 95°F.

The actual decrease in A/C efficiency is directly related to how low the refrigerant level is.  For this reason there is no average decrease in efficiency due to low refrigerant

Low refrigerant reduces the indoor cooling coil’s ability to cool indoor air.   If refrigerant level drops enough, the indoor cooling coil will begin to freeze.

Low refrigerant also lowers efficiency of the outdoor A/C unit.    The compressor in the outdoor unit is designed to operate with a specific amount of refrigerant.  If refrigerant gets low enough, the outdoor unit’s compressor will work longer and harder — shortening it’s lifespan.

Let’s Do The Math — If You Have All These:

leaking ductwork (10-25%)

dirty furnace air filter (up to 15%)

dirty indoor cooling coil (at least 15%)

dirty outdoor unit coil (up to 30%)

20% low on refrigerant (up to 24%)

Your cooling bill is as much as +109% higher than if these items were properly maintained!   

These same percentages apply to how much faster the A/C is wearing out.   

If the HVAC System has to run twice as long — it wears out twice as fast. 

 

All of These Problems Will Be Identified With A Spring A/C Tune Up.   

 

Our Summary Of The Scientific Report For Declining Air Conditioner Efficiency With Age

Using an analytical approach, air conditioning performance falls around 3.7% per year, on average.  This suggests that mechanical cooling system performance degrades over time in a measurable fashion if tracked by weather-related influences.

  • Decreasing Air Conditioner Efficiency Is Primarily Attributed To: System Age, Seasonal Energy Efficiency Ratio (SEER), and System Size.
  • System size/capacity appears to be the largest factor for declining efficiency.   Larger systems appeared have higher levels of decreasing efficiency — and they have shorter life expectancy.
  • For each additional 1 ton (12,000 BTU) — cooling efficiency an additional decreased in efficiency up to +3% per year occurs.
  • This may be due to larger systems operating at much higher air-flow rates.   This contributes to higher levels of air-filter clogging and indoor cooling-coil fouling.
  • Another contributing factor is if the existing ductwork & registers are undersized.
  • The cooler the home is kept, the more the A/C must run — and the faster the system wears out.
  • This is also the case in homes with insufficient insulation.
  • Higher SEER equipment appeared more resistant to decreasing efficiency.
  • SEER is a rating of Central A/C efficiency.  A newly installed unit in DFW must be SEER 14 or higher.
  • A 3-ton system with a SEER- 20 efficiency declined up to -1% less per year.
  • The study determined an average annual decrease in cooling efficiency of 5.2% per year in the Florida homes studied.
  • The Dept. Of Energy (DOE) stated 3% per year — but this number likely represents homes all over the U.S.
  • An air conditioner in Minneapolis runs a lot less than one in Florida.  The less it runs, the less cooling-efficiency will decrease per year.
  • With an average decline of -5.2% — system declines ranged from -8% to -40% per year.
  • The study found the amount of annual cooling-efficiency decline became higher as the system aged.
  • Sudden & severe declines in performance typically indicated the need for system replacement.

 

Another Factor That Dramatically Increases Cooling & Heating Costs

Inadequate Insulation.

Texas Homes Insulation Levels That Were Common — Or Became Required By Building-Code

           Attic Insulation                           Wall Insulation

  • 1950’s: none                                     none
  • 1965-1970: R-13 (3.5″ BATT)      Wall Insulation: R-6 (2″ BATT)
  • 1970’s:  R-19 (6″ BATT)                 Wall R-6  (2″ BATT)     *3
  • 1980’s: R-30 (9″ Blown)               Wall R-13 (3.5″ BATT)  *4
  • 2014:    R-38 (15″ Blown)              Wall R-15                         *5
  • *3 Source: https://snuggpro.com/blog/item/many-homes-built-prior-to-1980-were-built-without-insulation-in-the-walls
  • *4 Source: https://www.jlconline.com/how-to/insulation-code-change_o
  • *5 As required by the 2012 Edition of the International Building Code (IBC)

 

Ways To Lower Cooling & Heating Costs Without Replacing HVAC System.  

Click Below For Our Articles Detailing These Savings’ Opportunities: 

  • 25 Uncommon Ways To Lower Heating & Cooling Costs: https://www.alsplumbing.com/lower-heating-costs-20-uncommon-ways-part-1-of-3/

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The article was about declining central air conditioner efficiency as it ages.  Al’s Plumbing, Heating & A/C in Plano, Texas provides maintenance & repairs for all brands of Central A/C, Gas & Electric Furnace, and Heat Pumps.  Additionally we sell and install new HVAC Systems from American Standard (same company as Trane), Ameristar (same company as American Standard) and Coleman HVAC (same company as York HVAC).

Al’s also provides full service plumbing maintenance, repairs and replacements for every plumbing component in your home.  Al’s sells and installs Rheem Professional Series gas & electric water heaters, and tankless water heaters.  Al’s is near your home in Richardson, TX; Garland, TX; and northeast Dallas, TX.  We service all homes in southern Collin and Denton Counties with no additional travel charge.

Call Al’s today to discuss any concerns or problems you have with your HVAC System or Plumbing.  We will arrange an appointment at your convenience and offer 24/7 Emergency Service.